How can you open a file with exclusive access so no other process can read/write it?

Question

ICSM Computer · Answer

To open a file with exclusive access in C#, you can use the 
FileStream constructor and explicitly set the FileShare mode to
None.
Example: Open a file with exclusive access
using System;
using System.IO;
public class ExclusiveFileAccess
{
    public static FileStream OpenExclusive(string path)
    {
        return new FileStream(
            path,
            FileMode.OpenOrCreate,     // Open existing or create new
            FileAccess.ReadWrite,      // Allow reading and writing
            FileShare.None             // Do not allow any other access
        );
    }
}
FileShare.None means:
No other process or thread can open the file — not for reading, writing, or even deleting — until the stream is closed.
Usage
try
{
    using var stream = ExclusiveFileAccess.OpenExclusive("data.txt");
    using var writer = new StreamWriter(stream);
    writer.WriteLine("This file is locked for exclusive access.");
}
catch (IOException ex)
{
    Console.WriteLine("Could not access file exclusively: " + ex.Message);
}
Summary of FileShare Options
FileShare Option
Allows Other Processes To...
None
No access (exclusive)
Read
Read only
Write
Write only
ReadWrite
Read and write
Delete
Delete
Notes
Always use a using block or
Dispose() to release the lock promptly.On Windows, if another process tries to open the file while you have it open with
FileShare.None, it will throw an IOException.On Linux, file locking behavior is advisory (not enforced by the OS unless using additional mechanisms like
fcntl).

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How can you open a file with exclusive access so no other process can read/write it?

ICSM Computer

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1 Answers

Example: Open a file with exclusive access

`FileShare.None` means:

Usage

Summary of `FileShare` Options

Notes

Liked By

FileShare Option	Allows Other Processes To...
`None`	No access (exclusive)
`Read`	Read only
`Write`	Write only
`ReadWrite`	Read and write
`Delete`	Delete